1. Field of the Invention
The present invention relates to blower motor startup and more specifically to starting a blower motor in a motor vehicle with a locked rotor condition.
2. Background Art
Heating, ventilation and air conditioning (HVAC) systems are used in vehicles to provide comfort to passengers in the interior cabin of the vehicle by blowing air into the cabin at a designated temperature. Such HVAC systems commonly employ blower motors for receiving air, either ambient or recirculated, and blowing the air into the interior cabin of the vehicle through a series of ducts. Depending on the particular configuration of the HVAC system, a passenger may choose the temperature and/or flow rate of the air circulated by the blower motor.
As vehicles operate in a variety of environments, it is common for parts of the blower motor or the fan driven thereby to become obstructed by environmental debris such as twigs and leaves. When obstructed in such a manner, a blower motor can fail to start upon request or start may be delayed for some period of time, causing customer dissatisfaction. Sometimes when obstructed in such a manner, a passenger request for a high air flow rate from the motor can cause the motor to draw in excessively large currents, in turn damaging the motor and/or components used to drive the blower motor such as transistors. Accordingly, a need exists for a way to protect the blower motor during start-up and to also provide the passenger with a requested flow of air in a timely fashion.